They covered 1,100 kilometers (684 miles) with over 33,000 meters of elevation gain in 16 days, 16 hours and 56 minutes -- all under extreme weather conditions. The duo recently ran the entire border of Lesotho (pictured) in 16 days. Look through the gallery to see more of the world's most extreme foot races. Hide Caption 1 of 12 Photos: These are some of the most extreme foot races on Earth Everest: It's hard to imagine climbing Mount Everest -- let alone running it. Hide Caption 3 of 12 Photos: These are some of the most extreme foot races on Earth Iditarod Trail: Everest isn't the only cold-weather trail.

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